Glycosylation often plays a significant role in the biological function(s) of glycoconjugates (e.g., glycoproteins). For example, a glycoprotein's glycosylation pattern may affect its ability to fold correctly, its stability (e.g., resistance to proteolytic and/or other degradation), catalytic activity, pharmacodynamic and/or pharmacokinetic properties, and/or the ability of that glycoprotein to properly interact with other molecules. Alternatively or additionally, a glycoprotein's glycosylation pattern can affect transport and targeting of the glycoprotein, e.g., determining whether the glycoprotein remains intracellular (including, e.g., the correct targeting of the glycoprotein to the proper subcellular compartment or compartments), whether the glycoprotein will be membrane-bound and/or whether the glycoprotein will be secreted from the cell.
Individual glycoproteins often have more than one site for attachment of glycans by either N-linkages, O-linkages, or both. O-glycosylation processes produce a huge diversity of glycan structures. Given the importance of glycosylation in glycoprotein or glycoconjugate function, methods to characterize and quantify O-glycan species on glycoconjugates are needed.